#include "postgres.h"

#undef _

#include "fmgr.h"
#include "plperl.h"
#include "plperl_helpers.h"
#include "hstore.h"

PG_MODULE_MAGIC;

extern void _PG_init(void);

/* Linkage to functions in hstore module */
typedef HStore *(*hstoreUpgrade_t) (Datum orig);
static hstoreUpgrade_t hstoreUpgrade_p;
typedef int (*hstoreUniquePairs_t) (Pairs *a, int32 l, int32 *buflen);
static hstoreUniquePairs_t hstoreUniquePairs_p;
typedef HStore *(*hstorePairs_t) (Pairs *pairs, int32 pcount, int32 buflen);
static hstorePairs_t hstorePairs_p;
typedef size_t (*hstoreCheckKeyLen_t) (size_t len);
static hstoreCheckKeyLen_t hstoreCheckKeyLen_p;
typedef size_t (*hstoreCheckValLen_t) (size_t len);
static hstoreCheckValLen_t hstoreCheckValLen_p;


/*
 * Module initialize function: fetch function pointers for cross-module calls.
 */
void
_PG_init(void)
{
    /* Asserts verify that typedefs above match original declarations */
    AssertVariableIsOfType(&hstoreUpgrade, hstoreUpgrade_t);
    hstoreUpgrade_p = (hstoreUpgrade_t)
        load_external_function("$libdir/hstore", "hstoreUpgrade",
                               true, NULL);
    AssertVariableIsOfType(&hstoreUniquePairs, hstoreUniquePairs_t);
    hstoreUniquePairs_p = (hstoreUniquePairs_t)
        load_external_function("$libdir/hstore", "hstoreUniquePairs",
                               true, NULL);
    AssertVariableIsOfType(&hstorePairs, hstorePairs_t);
    hstorePairs_p = (hstorePairs_t)
        load_external_function("$libdir/hstore", "hstorePairs",
                               true, NULL);
    AssertVariableIsOfType(&hstoreCheckKeyLen, hstoreCheckKeyLen_t);
    hstoreCheckKeyLen_p = (hstoreCheckKeyLen_t)
        load_external_function("$libdir/hstore", "hstoreCheckKeyLen",
                               true, NULL);
    AssertVariableIsOfType(&hstoreCheckValLen, hstoreCheckValLen_t);
    hstoreCheckValLen_p = (hstoreCheckValLen_t)
        load_external_function("$libdir/hstore", "hstoreCheckValLen",
                               true, NULL);
}


/* These defines must be after the module init function */
#define hstoreUpgrade hstoreUpgrade_p
#define hstoreUniquePairs hstoreUniquePairs_p
#define hstorePairs hstorePairs_p
#define hstoreCheckKeyLen hstoreCheckKeyLen_p
#define hstoreCheckValLen hstoreCheckValLen_p


PG_FUNCTION_INFO_V1(hstore_to_plperl);

Datum
hstore_to_plperl(PG_FUNCTION_ARGS)
{
    dTHX;
    HStore       *in = PG_GETARG_HS(0);
    int            i;
    int            count = HS_COUNT(in);
    char       *base = STRPTR(in);
    HEntry       *entries = ARRPTR(in);
    HV           *hv;

    hv = newHV();

    for (i = 0; i < count; i++)
    {
        const char *key;
        SV           *value;

        key = pnstrdup(HSTORE_KEY(entries, base, i),
                       HSTORE_KEYLEN(entries, i));
        value = HSTORE_VALISNULL(entries, i) ? newSV(0) :
            cstr2sv(pnstrdup(HSTORE_VAL(entries, base, i),
                             HSTORE_VALLEN(entries, i)));

        (void) hv_store(hv, key, strlen(key), value, 0);
    }

    return PointerGetDatum(newRV((SV *) hv));
}


PG_FUNCTION_INFO_V1(plperl_to_hstore);

Datum
plperl_to_hstore(PG_FUNCTION_ARGS)
{
    dTHX;
    HV           *hv = (HV *) SvRV((SV *) PG_GETARG_POINTER(0));
    HE           *he;
    int32        buflen;
    int32        i;
    int32        pcount;
    HStore       *out;
    Pairs       *pairs;

    pcount = hv_iterinit(hv);

    pairs = palloc(pcount * sizeof(Pairs));

    i = 0;
    while ((he = hv_iternext(hv)))
    {
        char       *key = sv2cstr(HeSVKEY_force(he));
        SV           *value = HeVAL(he);

        pairs[i].key = pstrdup(key);
        pairs[i].keylen = hstoreCheckKeyLen(strlen(pairs[i].key));
        pairs[i].needfree = true;

        if (!SvOK(value))
        {
            pairs[i].val = NULL;
            pairs[i].vallen = 0;
            pairs[i].isnull = true;
        }
        else
        {
            pairs[i].val = pstrdup(sv2cstr(value));
            pairs[i].vallen = hstoreCheckValLen(strlen(pairs[i].val));
            pairs[i].isnull = false;
        }

        i++;
    }

    pcount = hstoreUniquePairs(pairs, pcount, &buflen);
    out = hstorePairs(pairs, pcount, buflen);
    PG_RETURN_POINTER(out);
}
